Depth adjusters and interchangeable locators for screwdrivers

ABSTRACT

A depth adjuster made of injection molded plastic parts has a bit housing which screws onto the projecting externally threaded nose on the gear housing of a standard electric powered hand tool provided with a positive pressure engaged clutch. The bit housing has a bore to accommodate the clutch chuck and the shank of a bit for a screw head. The bore passes through an extending neck on the bit housing which is externally threaded and provided with an outwardly facing shoulder having locking tabs. Onto this neck is threaded a locator assembly of a type designed for a particular application. This assembly has three parts which are snapped into place and remain assembled even when disconnected from the bit housing. These parts consist of (1) a locking collar with locking slots which engage with the locking tabs, (2) a locator sleeve which has limited axial movement and a non-rotative movement with respect to the locking collar, and (3) a compression spring which axially urges the locking collar rearwardly toward the outer extreme of its limited motion with respect to the locator sleeve.

United States Patent 1 Lafferty, Sr.

[ Jan. 23, 1973 DEPTH ADJUSTERS AND INTERCHANGEABLE LOCATORS FORSCREWDRIVERS [75] Inventor: Gary S. Lafferty, Sr., Milwaukee,

Wis.

[73] Assignee: Milwaukee Electric Tool Corporation, Brookfield, Wis.

[22] Filed: May 6, 1971 [21] Appl. No.: 140,728

UNITED STATES PATENTS 3,527,273 9/1970 Falter ..l44/32 2,790,47l 4/1957Graybill ..l44/32 2,940,488 6/1960 Riley ..l44/32 3,454,059 7/1969Sindelar... ..I44/32 3,298,410 l/l967 Morifuji ..l44/324 PrimaryExaminerDonald R. Schran Attorney-John W. Michael, Gerrit D. Foster,Bayard H. Michael, Paul R. Puerner, Joseph A. Gemigani, Robert E.Clemency, Andrew 0. Riteris, Glenn A. Buse and Spencer B. Michael [5 7]ABSTRACT A depth adjuster made of injection molded plastic parts has abit housing which screws onto the projecting externally threaded nose onthe gear housing of a standard electric powered hand tool provided witha positive pressure engaged clutch. The bit housing has a bore toaccommodate the clutch chuck and the shank of a bit for a screw head.The bore passes through an extending neck on the bit housing which isexternally threaded and provided with an outwardly facing shoulderhaving locking tabs. Onto this neck is threaded a locator assembly of atype designed for a particular application. This assembly has threeparts which are snapped into place and remain assembled even whendisconnected from the bit housing. These parts consist of (1) a lockingcollar with locking slots which engage with the locking tabs, (2) alocator sleeve which has limited axial movement and a nonrotativemovement with respect to the locking collar, and (3) a compressionspring which axially urges the locking collar rearwardly toward theouter extreme of its limited motion with respect to the locator sleeve.

7 Claims, 8 Drawing Figures PATENTEUJANZB I973 I 3.712.352

sum 1 OF 2 @ZWPW DEPTH ADJUSTERS AND INTERCHANGEABLE LOCATORS FORSCREWDRIVERS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to an improved depth adjuster for electric poweredhand tools used to apply self drilling, self tapping fasteners, drywallfasteners, and the like. The invention specifically features: the use ofinjection molded parts; a locator assembly which cannot be disassembledwithout destruction; a standardized bit housing; and a standardizedlocking collar and locking collar spring with which a variety oflocating sleeves for different applications can be assembled to providelocator assemblies suited for use in particular applications.

2. Description of the Prior Art Depth adjusters for positive clutchelectric powered hand tools used to apply fasteners including: (1) a bithousing to be mounted on the tool; (2) a locking collar; (3) a locatorsleeve threadably mounted on the bit housing; and (4) a locking collarspring are well known prior art. Examples are shown and described inU.S. Pat. No. 2,940,488 issued June 14, 1960, and in the Service PartsList of Milwaukee Electric Tool Corp. identified as Bul. 54-42-5102Catalog No. 6746-1 and Bul. 54-42-5454 Catalog No. 6796-1 (copies ofwhich are attached for including in the tile of this application).

In current practice the parts of the prior art depth adjusters arefabricated from steel at relatively high cost. Also a decided detractoris that the parts can be easily disassembled and when this is doneparts, particularly the spring, are lost.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a fragmentary view in axial cross-section of an electricpowered hand tool having applied to it a depth adjuster embodying thepresent invention;

FIG. 2 is an exploded view in perspective showing the bit housing andlocator assembly constituting parts of the depth adjuster embodying thepresent invention;

FIG. 3 is an exploded view in perspective showing the elementscomprising the locator assembly;

FIG. 4 is an axial sectional view of the locator assembly;

FIG. 5 is a sectional view similar to FIG. 1 showing the parts whendriving the screw with the clutch in engagement;

FIG. 6 is a sectional view similar to the view FIG. 5 showing the partsin stopped position with screw head flush with the work surface;

FIG. 7 is a sectional view similar to that of FIG. 6 showing the depthadjuster adjusted to stop driving action prior to the complete settingof the screw; and

FIG. 8 is a sectional view similar to the view of FIG. 5 showing a depthadjuster and locator sleeve adjusted to seat a screw below the surfaceof a workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings byreference numerals, there is illustrated for the purpose of describingthis invention an electric powered hand drill the design of which makesit particularly suitable for driving screws of various natures. Thisdrill has a clutch gear 10 mounted within its gear housing 11. Thisclutch gear receives motor torque through its geared teeth and transmitsit to its clutch teeth. Mounted within an extending neck 13 of the gearhousing is a clutch chuck 12 which is carried in a roller bearing 14.This clutch chuck has a standard non-circular bore for receiving theshank of a bit. The interchanging teeth and recesses of the clutch gearand the clutch chunk are of standard well-known design. Not shown is aspring which urges the clutch chuck forwardly to the non-drivingposition shown in FIG. 1. When force is applied by the tool operator tothe drill the driving bit forces the clutch chuck rearwardly into thedriving position shown in FIG. 5. This part of the drill and positiveclutch are not part of this invention and are described to show thenature of the drill to which the depth adjuster of this invention isattached.

Mounted on the neck 13 is a bit housing 16. This bit housing is formedby injection molding of a plastic known in the trade as Black NylatronGS, a product of The Polymer Corp. It is a molybdenum-disulfide fillednylon moisture stabilized at 2 percent water content. It has an internalbore with an enlarged inner end with internal threads and an outerprojecting neck 18 provided with external male adjustment threads 19. Ascrewdriving bit 20 of conventional design is housed in this bit housingand conventionally engaged with the clutch chuck 12. A locator assemblylater described in detail is supported on the neck 18. As shown in FIG.2 lands 22 and recesses 24 are formed in angular spaced relation on theoutside of the enlarged end. Four angularly spaced reference arrows mayalso be formed on certain of the lands 22 to show the relativerotational positions between the bit housing and locking collar. Animportant part of the bit housing is the forwardly facing surface 26from which project locking tabs 28 the purpose of which will behereinafter described.

A feature of this invention is the locator assembly shown in theexploded views of FIGS. 2 and 3 before its parts are assembled and inthe assembled view of FIG. 4 with its parts assembled. This assemblyconsists of three mechanical elements: (1) a locking collar 30; (2) alocator sleeve 32; and (3) a compression spring 34. When these areassembled as shown in FIG. 4 they may not be disassembled withoutdestroying the interlocking feature hereinafter described. The advantageof this is that the operator in making an adjustment for depth controlcannot accidentally disassemble the parts and in particular allow thespring to fly out of position and become lost.

The locking collar 30 is also formed by injection molding of the samematerial as set forth above in the description of the bit housing 16. Ithas an internal bore 36 in which the spring 34 is contained. As clearlyshown in FIG. 2 it has an intumed flange 38 at the inner end of thebore. The inner flange 38 has angularly spaced locking slots 42 intowhich the locking tabs 26 on the bit housing fit when aligned to preventrelative rotation between the bit housing 16 and the locking collar 30during normal operation of the driver. Each time there is an alignmentbetween the tabs 28 and the slots 42 the compression spring 34 actingbetween inner end of the locator sleeve and the flange 38 forces theslots 42 toward and into engagement with the tabs 28. The locking collar30 is preferably provided with angularly spaced lands 44 and recesses46. Reference numerals such as 1 through 4 may also be formed on certainspaced lands 44 to align the reference arrows on the bit housing withreference members to help the operator change adjustment as laterdescribed.

The locking collar 30 with compression spring 34 wormed into the bore 36comprises a standardized subassembly which is the same size for eachdifferent complete assembly which includes locator sleeves designed fordifferent applications. Since the mechanical characteristics of thevarious locator sleeves which cooperate with locking collar and springsubassembly and the adjuster thread 19 on the bit housing are the same,only one a so-called standard locator sleeve will be described indetail. The other mechanical shapes or characteristics which adopt theapplicator for special uses, sometimes identified as washer head,drywall head, and limited clearance head are old in this art and do notform part of this invention other than to relate that such shapes asarerequired and which were heretofore fabricated from metal can beformed by injection molding in the same manner and from the samematerial as described for the bit housing.

As shown in FIGS. 3 and 4, an inturned flange 40 at the outer end of thebore 36 of the locking collar has angularly spaced slots 48 into whichare slidably fitted longitudinally extending angularly spaced lands 50on the locator sleeve 32. Between such lands the locator sleeve hasrearwardly extending flexible fingers 52 the ends of which supportradially projecting locking teeth 54. The forward surface of these teethis sloped as shown in FIG. 4 so that during assembly the fingers will beinwardly depressed by the angularly spaced portions of the flange 40 andas these teeth slide inwardly and pass beyond such portions they will besprung outwardly to the position shown in FIG. 4 and the teeth willengage the inner face of such portions to prevent disassembly of thelocator sleeve from the locking collar.

The locator sleeve 32 is shaped as shown in FIG. 2 and is classified asstandard. It has a frusto-conical nose 56 and a central bore 58. At theinner end of this bore are internal female adjustment threads 60 whichmate with the external threads 19 on the neck of the bit housing in themanner shown in FIG. 1.

The adjustment threads on the locator sleeve and bit housing are at apitch of 16 threads per inch. Thus, as the locator sleeve assembly isrotated, each full revolution represents one-sixteenth inch axialmovement. The assembly may be locked in one-fourth turn increments,resulting in a fine adjustment in one sixty-fourths inch increments. Forthe convenience of the user, the numbers 1 through 4 on the perimeter ofthe locking collar can be aligned with four arrows on the bit housing.As a result, when the operator wishes to change the adjustment onethirty-seconds inch, he may choose any arrow and using it as a referencepoint, rotate the locator sleeve assembly two numbers, correspondinglychanging the adjustment two sixty-fourths inch.

Since the locking collar may be moved axially with respect to thelocator sleeve and rotated to also rotate the locator sleeve theoperator may make the adjustment by one hand. The systems presentlyoffered require two hands to make an adjustment, one must hold thelocking collar and the other turn the locator sleeve.

As previously stated locator sleeves may be offered with variouscharacteristics to create different assemblies. It has been foundadvantageous to provide complete factory made and inspected locatorassemblies as this insures that the quality of the fit between thelocator sleeve and the screwdriving bit is readily maintained over aprolonged period. The .lubricant which is inherent in the thermoplasticmaterial used in these assemblies will prolong the life of therelatively expensive screwdriving bit and prolong the life of thedesired quality of fit. This is not true of the assemblies manufacturedfrom steel.

I claim:

1. A depth adjuster adapted for mounting on an electric powered handtool, said tool having a positive pressure engaged clutch including aclutch chuck for receiving a bit, and a gear housing having anexternally threaded neck, said adjuster comprising:

a. a bit housing threadedly mounted on the neck of the tool, said bithousing having spaced locking tabs and an adjusting thread; and

b. a locator assembly consisting of (1) a locking collar with spacedlocking slots into which said locking tabs fit, (2) a locator sleevecarried by said locking collar and having limited axial movement andnon-rotative movement with respect thereto, said locator sleeve havingan adjusting thread engaged with the adjusting thread on said bithousing, and (3) a compression spring acting directly between saidlocking collar and said locator sleeve to move said locator sleeve tothe outer limit of its limited axial movement with respect to saidlocator sleeve.

2. A depth adjuster as defined in claim 1 wherein the limited axialmovement of said locking collar relative to said locator sleeve isaccomplished by connecting means including a resilient member on onewhich snaps into engagement with an abutment on the other of saidlocking collar or locator sleeve.

3. A depth adjuster as defined in claim 2 wherein said connecting meansprevents disassembly of the locator assembly without destruction ofconnecting means.

4. A depth adjuster as defined in claim 1 wherein said bit housing, saidlocking collar and said locator sleeve are plastic parts formed byinjection molding of plastic identified as molybdenum-disulfide fillednylon.

5. A depth adjuster as defined in claim 4 wherein:

a. said locking means consists of locking tabs projecting from aforwardly facing surface on the bit housings; and

b. said locking means on said bit housing consists of spaced lockingslots in an inner flange into which said locking tabs fit when alignedto prevent relative rotation between said bit housing and said lockingcollar to maintain the required depth adjustment.

A depth adjuster as defined in claim 5 wherein:

a. said locking collar has an internal bore in which said compressionspring is contained and an inturned flange at the outer end of said borewith angularly spaced slots; and

d. said tabs and slots being angularly spaced with relation to saidpitch so that the operator may change the depth adjustment by twosixth-fourths inch by rotating said locator sleeve so that a referencemarking on said sleeve is moved into alignment with a reference markingon said bit housing spaced two lands from the reference marking on saidbit housing with which reference marking on said sleeve was initiallyaligned.

1. A depth adjuster adapted for mounting on an electric powered handtool, said tool having a positive pressure engaged clutch including aclutch chuck for receiving a bit, and a gear housing having anexternally threaded neck, said adjuster comprising: a. a bit housingthreadedly mounted on the neck of the tool, said bit housing havingspaced locking tabs and an adjusting thread; and b. a locator assemblyconsisting of (1) a locking collar with spaced locking slots into whichsaid locking tabs fit, (2) a locator sleeve carried by said lockingcollar and having limited axial movement and non-rotative movement withrespect thereto, said locator sleeve having an adjusting thread engagedwith the adjusting thread on said bit housing, and (3) a compressionspring acting directly between said locking collar and said locatorsleeve to move said locator sleeve to the outer limit of its limitedaxial movement with respect to said locator sleeve.
 2. A depth adjusteras defined in claim 1 wherein the limited axial movement of said lockingcollar relative to said locator sleeve is accomplished by connectingmeans including a resilient member on one which snaps into engagementwith an abutment on the other of said locking collar or locator sleeve.3. A depth adjuster as defined in claim 2 wherein said connecting meansprevents disassembly of the locator assembly without destruction ofconnecting means.
 4. A depth adjuster as defined in claim 1 wherein saidbit housing, said locking collar and said locator sleeve are plasticparts formed by injection molding of plastic identified asmolybdenum-disulfide filled nylon.
 5. A depth adjuster as defined inclaim 4 wherein: a. said locking means consists of locking tabsprojecting from a forwardly facing surface on the bit housings; and b.said locking means on said bit housing consists of spaced locking slotsin an inner flange into which said locking tabs fit when aligned toprevent relative rotation between said bit housing and said lockingcollar to maintain the required depth adjustment.
 6. A depth adjuster asdefined in claim 5 wherein: a. said locking collar has an internal borein which said compression spring is contained and an inturned flange atthe outer end of said bore with angularly spaced slots; and b. saidlocator sleeve has angularly spaced lands slidable in said slots topermit relative axial movement between said collar and said sleeve whilepreventing relative rotation therebetween.
 7. A depth adjuster asdefined in claim 6 wherein: a. said adjusting threads are at a pitch of16 threads per inch; b. said bit housing has angularly spaced landshaving a reference marking visibly mounted thereon; c. said lands onsaid locator sleeve have a reference marking visibly mounted thereon;and d. said tabs and slots being angularly spaced with relation to saidpitch so that the operator may change the depth adjustment by twosixty-fourths inch by rotating said locator sleeve so that a referencemarking on said sleeve is moved into alignment with a reference markingon said bit housing spaced two lands from the reference marking on saidbit housing with which reference marking on said sleeve was initiallyaligned.